The peculiar galactic center neutron star x-ray binary XMM J174457-2850.3

N. Degenaar, R. Wijnands, M. T. Reynolds, J. M. Miller, D. Altamirano, J. Kennea, N. Gehrels, D. Haggard, G. Ponti

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23 Scopus citations


The recent discovery of a millisecond radio pulsar experiencing an accretion outburst similar to those seen in low mass X-ray binaries, has opened up a new opportunity to investigate the evolutionary link between these two different neutron star manifestations. The remarkable X-ray variability and hard X-ray spectrum of this object can potentially serve as a template to search for other X-ray binary/radio pulsar transitional objects. Here we demonstrate that the transient X-ray source XMM J174457-2850.3 near the Galactic center displays similar X-ray properties. We report on the detection of an energetic thermonuclear burst with an estimated duration of ≃2 hr and a radiated energy output of ≃ 5 × 1040 erg, which unambiguously demonstrates that the source harbors an accreting neutron star. It has a quiescent X-ray luminosity of L X ≃ 5 × 10 32(D/6.5 kpc)2 erg s-1 and exhibits occasional accretion outbursts during which it brightens to L X ≃ 10 35-1036(D/6.5 kpc)2 erg s-1 for a few weeks (2-10 keV). However, the source often lingers in between outburst and quiescence at L X ≃ 1033-1034(D/6.5 kpc)2 erg s-1. This peculiar X-ray flux behavior and its relatively hard X-ray spectrum, a power law with an index of Γ ≃ 1.4, could possibly be explained in terms of the interaction between the accretion flow and the magnetic field of the neutron star.

Original languageEnglish (US)
Article number109
JournalAstrophysical Journal
Issue number2
StatePublished - Sep 10 2014

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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